Add USER SET parameter values for pg_db_role_setting

The USER SET flag specifies that the variable should be set on behalf of an
ordinary role.  That lets ordinary roles set placeholder variables, which
permission requirements are not known yet.  Such a value wouldn't be used if
the variable finally appear to require superuser privileges.

The new flags are stored in the pg_db_role_setting.setuser array.  Catversion
is bumped.

This commit is inspired by the previous work by Steve Chavez.

Discussion: https://postgr.es/m/CAPpHfdsLd6E--epnGqXENqLP6dLwuNZrPMcNYb3wJ87WR7UBOQ%40mail.gmail.com
Author: Alexander Korotkov, Steve Chavez
Reviewed-by: Pavel Borisov, Steve Chavez

doc/src/sgml/catalogs.sgml

@@ -3194,6 +3194,16 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
        Defaults for run-time configuration variables
       </para></entry>
      </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>setuser</structfield> <type>bool[]</type>
+      </para>
+      <para>
+       Values of <link linkend="sql-alterrole-user-set"><literal>USER SET</literal></link>
+       flag for every setting in <structfield>setconfig</structfield>
+      </para></entry>
+     </row>
     </tbody>
    </tgroup>
   </table>

doc/src/sgml/ref/alter_database.sgml

@@ -37,7 +37,7 @@ ALTER DATABASE <replaceable class="parameter">name</replaceable> SET TABLESPACE
 
 ALTER DATABASE <replaceable class="parameter">name</replaceable> REFRESH COLLATION VERSION
 
-ALTER DATABASE <replaceable class="parameter">name</replaceable> SET <replaceable>configuration_parameter</replaceable> { TO | = } { <replaceable>value</replaceable> | DEFAULT }
+ALTER DATABASE <replaceable class="parameter">name</replaceable> SET <replaceable>configuration_parameter</replaceable> { TO | = } { <replaceable>value</replaceable> | <replaceable>value</replaceable> USER SET | DEFAULT }
 ALTER DATABASE <replaceable class="parameter">name</replaceable> SET <replaceable>configuration_parameter</replaceable> FROM CURRENT
 ALTER DATABASE <replaceable class="parameter">name</replaceable> RESET <replaceable>configuration_parameter</replaceable>
 ALTER DATABASE <replaceable class="parameter">name</replaceable> RESET ALL
@@ -206,6 +206,19 @@ ALTER DATABASE <replaceable class="parameter">name</replaceable> RESET ALL
        </para>
       </listitem>
      </varlistentry>
+
+     <varlistentry>
+      <term><literal>USER SET</literal></term>
+      <listitem>
+       <para>
+        Specifies that variable should be set on behalf of ordinary role.
+        That lets non-superuser and non-replication role to set placeholder
+        variables, with permission requirements is not known yet;
+        see <xref linkend="runtime-config-custom"/>. The variable won't
+        be set if it appears to require superuser privileges.
+       </para>
+      </listitem>
+     </varlistentry>
   </variablelist>
  </refsect1>
 

doc/src/sgml/ref/alter_role.sgml

@@ -38,7 +38,7 @@ ALTER ROLE <replaceable class="parameter">role_specification</replaceable> [ WIT
 
 ALTER ROLE <replaceable class="parameter">name</replaceable> RENAME TO <replaceable>new_name</replaceable>
 
-ALTER ROLE { <replaceable class="parameter">role_specification</replaceable> | ALL } [ IN DATABASE <replaceable class="parameter">database_name</replaceable> ] SET <replaceable>configuration_parameter</replaceable> { TO | = } { <replaceable>value</replaceable> | DEFAULT }
+ALTER ROLE { <replaceable class="parameter">role_specification</replaceable> | ALL } [ IN DATABASE <replaceable class="parameter">database_name</replaceable> ] SET <replaceable>configuration_parameter</replaceable> { TO | = } { <replaceable>value</replaceable> | <replaceable>value</replaceable> USER SET | DEFAULT }
 ALTER ROLE { <replaceable class="parameter">role_specification</replaceable> | ALL } [ IN DATABASE <replaceable class="parameter">database_name</replaceable> ] SET <replaceable>configuration_parameter</replaceable> FROM CURRENT
 ALTER ROLE { <replaceable class="parameter">role_specification</replaceable> | ALL } [ IN DATABASE <replaceable class="parameter">database_name</replaceable> ] RESET <replaceable>configuration_parameter</replaceable>
 ALTER ROLE { <replaceable class="parameter">role_specification</replaceable> | ALL } [ IN DATABASE <replaceable class="parameter">database_name</replaceable> ] RESET ALL
@@ -234,6 +234,19 @@ ALTER ROLE { <replaceable class="parameter">role_specification</replaceable> | A
        </para>
       </listitem>
      </varlistentry>
+
+     <varlistentry id="sql-alterrole-user-set">
+      <term><literal>USER SET</literal></term>
+      <listitem>
+       <para>
+        Specifies that variable should be set on behalf of ordinary role.
+        That lets non-superuser and non-replication role to set placeholder
+        variables, with permission requirements is not known yet;
+        see <xref linkend="runtime-config-custom"/>. The variable won't
+        be set if it appears to require superuser privileges.
+       </para>
+      </listitem>
+     </varlistentry>
     </variablelist>
  </refsect1>
 
@@ -329,6 +342,13 @@ ALTER ROLE worker_bee SET maintenance_work_mem = 100000;
 
 <programlisting>
 ALTER ROLE fred IN DATABASE devel SET client_min_messages = DEBUG;
+</programlisting></para>
+
+  <para>
+   Give a role a non-default placeholder setting on behalf of ordinary user:
+
+<programlisting>
+ALTER ROLE fred SET my.param = 'value' USER SET;
 </programlisting></para>
  </refsect1>
 

doc/src/sgml/ref/alter_user.sgml

@@ -38,7 +38,7 @@ ALTER USER <replaceable class="parameter">role_specification</replaceable> [ WIT
 
 ALTER USER <replaceable class="parameter">name</replaceable> RENAME TO <replaceable>new_name</replaceable>
 
-ALTER USER { <replaceable class="parameter">role_specification</replaceable> | ALL } [ IN DATABASE <replaceable class="parameter">database_name</replaceable> ] SET <replaceable>configuration_parameter</replaceable> { TO | = } { <replaceable>value</replaceable> | DEFAULT }
+ALTER USER { <replaceable class="parameter">role_specification</replaceable> | ALL } [ IN DATABASE <replaceable class="parameter">database_name</replaceable> ] SET <replaceable>configuration_parameter</replaceable> { TO | = } { <replaceable>value</replaceable> | <replaceable>value</replaceable> USER SET | DEFAULT }
 ALTER USER { <replaceable class="parameter">role_specification</replaceable> | ALL } [ IN DATABASE <replaceable class="parameter">database_name</replaceable> ] SET <replaceable>configuration_parameter</replaceable> FROM CURRENT
 ALTER USER { <replaceable class="parameter">role_specification</replaceable> | ALL } [ IN DATABASE <replaceable class="parameter">database_name</replaceable> ] RESET <replaceable>configuration_parameter</replaceable>
 ALTER USER { <replaceable class="parameter">role_specification</replaceable> | ALL } [ IN DATABASE <replaceable class="parameter">database_name</replaceable> ] RESET ALL

doc/src/sgml/ref/psql-ref.sgml

@@ -1897,6 +1897,13 @@ INSERT INTO tbl1 VALUES ($1, $2) \bind 'first value' 'second value' \g
         commands are used to define per-role and per-database configuration
         settings.
         </para>
+
+        <para>
+        Since <productname>PostgreSQL</productname> 16 the output includes
+        column with the values of
+        <link linkend="sql-alterrole-user-set"><literal>USER SET</literal></link>
+        flag for each setting.
+        </para>
         </listitem>
       </varlistentry>
 

src/backend/catalog/pg_db_role_setting.c

@@ -63,14 +63,23 @@ AlterSetting(Oid databaseid, Oid roleid, VariableSetStmt *setstmt)
 		if (HeapTupleIsValid(tuple))
 		{
 			ArrayType  *new = NULL;
+			ArrayType  *usersetArray;
 			Datum		datum;
+			Datum		usersetDatum;
 			bool		isnull;
+			bool		usersetIsnull;
 
 			datum = heap_getattr(tuple, Anum_pg_db_role_setting_setconfig,
 								 RelationGetDescr(rel), &isnull);
+			usersetDatum = heap_getattr(tuple, Anum_pg_db_role_setting_setuser,
+										RelationGetDescr(rel), &usersetIsnull);
 
 			if (!isnull)
-				new = GUCArrayReset(DatumGetArrayTypeP(datum));
+			{
+				Assert(!usersetIsnull);
+				usersetArray = DatumGetArrayTypeP(usersetDatum);
+				new = GUCArrayReset(DatumGetArrayTypeP(datum), &usersetArray);
+			}
 
 			if (new)
 			{
@@ -86,6 +95,11 @@ AlterSetting(Oid databaseid, Oid roleid, VariableSetStmt *setstmt)
 				repl_repl[Anum_pg_db_role_setting_setconfig - 1] = true;
 				repl_null[Anum_pg_db_role_setting_setconfig - 1] = false;
 
+				repl_val[Anum_pg_db_role_setting_setuser - 1] =
+					PointerGetDatum(usersetArray);
+				repl_repl[Anum_pg_db_role_setting_setuser - 1] = true;
+				repl_null[Anum_pg_db_role_setting_setuser - 1] = false;
+
 				newtuple = heap_modify_tuple(tuple, RelationGetDescr(rel),
 											 repl_val, repl_null, repl_repl);
 				CatalogTupleUpdate(rel, &tuple->t_self, newtuple);
@@ -101,28 +115,39 @@ AlterSetting(Oid databaseid, Oid roleid, VariableSetStmt *setstmt)
 		bool		repl_repl[Natts_pg_db_role_setting];
 		HeapTuple	newtuple;
 		Datum		datum;
+		Datum		usersetDatum;
 		bool		isnull;
+		bool		usersetIsnull;
 		ArrayType  *a;
+		ArrayType  *usersetArray;
 
 		memset(repl_repl, false, sizeof(repl_repl));
 		repl_repl[Anum_pg_db_role_setting_setconfig - 1] = true;
 		repl_null[Anum_pg_db_role_setting_setconfig - 1] = false;
+		repl_repl[Anum_pg_db_role_setting_setuser - 1] = true;
+		repl_null[Anum_pg_db_role_setting_setuser - 1] = false;
 
-		/* Extract old value of setconfig */
+		/* Extract old values of setconfig and setuser */
 		datum = heap_getattr(tuple, Anum_pg_db_role_setting_setconfig,
 							 RelationGetDescr(rel), &isnull);
 		a = isnull ? NULL : DatumGetArrayTypeP(datum);
 
+		usersetDatum = heap_getattr(tuple, Anum_pg_db_role_setting_setuser,
+									RelationGetDescr(rel), &usersetIsnull);
+		usersetArray = usersetIsnull ? NULL : DatumGetArrayTypeP(usersetDatum);
+
 		/* Update (valuestr is NULL in RESET cases) */
 		if (valuestr)
-			a = GUCArrayAdd(a, setstmt->name, valuestr);
+			a = GUCArrayAdd(a, &usersetArray, setstmt->name, valuestr, setstmt->user_set);
 		else
-			a = GUCArrayDelete(a, setstmt->name);
+			a = GUCArrayDelete(a, &usersetArray, setstmt->name);
 
 		if (a)
 		{
 			repl_val[Anum_pg_db_role_setting_setconfig - 1] =
 				PointerGetDatum(a);
+			repl_val[Anum_pg_db_role_setting_setuser - 1] =
+				PointerGetDatum(usersetArray);
 
 			newtuple = heap_modify_tuple(tuple, RelationGetDescr(rel),
 										 repl_val, repl_null, repl_repl);
@@ -137,16 +162,18 @@ AlterSetting(Oid databaseid, Oid roleid, VariableSetStmt *setstmt)
 		HeapTuple	newtuple;
 		Datum		values[Natts_pg_db_role_setting];
 		bool		nulls[Natts_pg_db_role_setting];
-		ArrayType  *a;
+		ArrayType  *a,
+				   *usersetArray;
 
 		memset(nulls, false, sizeof(nulls));
 
-		a = GUCArrayAdd(NULL, setstmt->name, valuestr);
+		a = GUCArrayAdd(NULL, &usersetArray, setstmt->name, valuestr, setstmt->user_set);
 
 		values[Anum_pg_db_role_setting_setdatabase - 1] =
 			ObjectIdGetDatum(databaseid);
 		values[Anum_pg_db_role_setting_setrole - 1] = ObjectIdGetDatum(roleid);
 		values[Anum_pg_db_role_setting_setconfig - 1] = PointerGetDatum(a);
+		values[Anum_pg_db_role_setting_setuser - 1] = PointerGetDatum(usersetArray);
 		newtuple = heap_form_tuple(RelationGetDescr(rel), values, nulls);
 
 		CatalogTupleInsert(rel, newtuple);
@@ -240,20 +267,25 @@ ApplySetting(Snapshot snapshot, Oid databaseid, Oid roleid,
 	while (HeapTupleIsValid(tup = systable_getnext(scan)))
 	{
 		bool		isnull;
+		bool		usersetIsnull;
 		Datum		datum;
+		Datum		usersetDatum;
 
 		datum = heap_getattr(tup, Anum_pg_db_role_setting_setconfig,
 							 RelationGetDescr(relsetting), &isnull);
+		usersetDatum = heap_getattr(tup, Anum_pg_db_role_setting_setuser,
+									RelationGetDescr(relsetting), &usersetIsnull);
 		if (!isnull)
 		{
 			ArrayType  *a = DatumGetArrayTypeP(datum);
+			ArrayType  *usersetArray = DatumGetArrayTypeP(usersetDatum);
 
 			/*
 			 * We process all the options at SUSET level.  We assume that the
 			 * right to insert an option into pg_db_role_setting was checked
 			 * when it was inserted.
 			 */
-			ProcessGUCArray(a, PGC_SUSET, source, GUC_ACTION_SET);
+			ProcessGUCArray(a, usersetArray, PGC_SUSET, source, GUC_ACTION_SET);
 		}
 	}
 

src/backend/catalog/pg_proc.c

@@ -698,6 +698,7 @@ ProcedureCreate(const char *procedureName,
 			{
 				save_nestlevel = NewGUCNestLevel();
 				ProcessGUCArray(set_items,
+								NULL,
 								(superuser() ? PGC_SUSET : PGC_USERSET),
 								PGC_S_SESSION,
 								GUC_ACTION_SAVE);

src/backend/commands/functioncmds.c

@@ -662,9 +662,9 @@ update_proconfig_value(ArrayType *a, List *set_items)
 			char	   *valuestr = ExtractSetVariableArgs(sstmt);
 
 			if (valuestr)
-				a = GUCArrayAdd(a, sstmt->name, valuestr);
+				a = GUCArrayAdd(a, NULL, sstmt->name, valuestr, sstmt->user_set);
 			else				/* RESET */
-				a = GUCArrayDelete(a, sstmt->name);
+				a = GUCArrayDelete(a, NULL, sstmt->name);
 		}
 	}
 

src/backend/parser/gram.y

@@ -1621,6 +1621,26 @@ generic_set:
 					n->args = $3;
 					$$ = n;
 				}
+			| var_name TO var_list USER SET
+				{
+					VariableSetStmt *n = makeNode(VariableSetStmt);
+
+					n->kind = VAR_SET_VALUE;
+					n->name = $1;
+					n->args = $3;
+					n->user_set = true;
+					$$ = n;
+				}
+			| var_name '=' var_list USER SET
+				{
+					VariableSetStmt *n = makeNode(VariableSetStmt);
+
+					n->kind = VAR_SET_VALUE;
+					n->name = $1;
+					n->args = $3;
+					n->user_set = true;
+					$$ = n;
+				}
 			| var_name TO DEFAULT
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);

src/backend/utils/adt/arrayfuncs.c

@@ -3344,6 +3344,7 @@ construct_array_builtin(Datum *elems, int nelems, Oid elmtype)
 	switch (elmtype)
 	{
 		case CHAROID:
+		case BOOLOID:
 			elmlen = 1;
 			elmbyval = true;
 			elmalign = TYPALIGN_CHAR;

src/backend/utils/fmgr/fmgr.c

@@ -706,6 +706,7 @@ fmgr_security_definer(PG_FUNCTION_ARGS)
 	if (fcache->proconfig)
 	{
 		ProcessGUCArray(fcache->proconfig,
+						NULL,
 						(superuser() ? PGC_SUSET : PGC_USERSET),
 						PGC_S_SESSION,
 						GUC_ACTION_SAVE);

src/backend/utils/misc/guc.c

@@ -225,7 +225,6 @@ static bool reporting_enabled;	/* true to enable GUC_REPORT */
 
 static int	GUCNestLevel = 0;	/* 1 when in main transaction */
 
-
 static int	guc_var_compare(const void *a, const void *b);
 static uint32 guc_name_hash(const void *key, Size keysize);
 static int	guc_name_match(const void *key1, const void *key2, Size keysize);
@@ -245,7 +244,7 @@ static void reapply_stacked_values(struct config_generic *variable,
 								   GucContext curscontext, GucSource cursource,
 								   Oid cursrole);
 static bool validate_option_array_item(const char *name, const char *value,
-									   bool skipIfNoPermissions);
+									   bool user_set, bool skipIfNoPermissions);
 static void write_auto_conf_file(int fd, const char *filename, ConfigVariable *head);
 static void replace_auto_config_value(ConfigVariable **head_p, ConfigVariable **tail_p,
 									  const char *name, const char *value);
@@ -6182,7 +6181,6 @@ ParseLongOption(const char *string, char **name, char **value)
 	{
 		*name = palloc(equal_pos + 1);
 		strlcpy(*name, string, equal_pos + 1);
-
 		*value = pstrdup(&string[equal_pos + 1]);
 	}
 	else
@@ -6205,7 +6203,7 @@ ParseLongOption(const char *string, char **name, char **value)
  * The array parameter must be an array of TEXT (it must not be NULL).
  */
 void
-ProcessGUCArray(ArrayType *array,
+ProcessGUCArray(ArrayType *array, ArrayType *usersetArray,
 				GucContext context, GucSource source, GucAction action)
 {
 	int			i;
@@ -6218,6 +6216,7 @@ ProcessGUCArray(ArrayType *array,
 	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
 	{
 		Datum		d;
+		Datum		userSetDatum = BoolGetDatum(false);
 		bool		isnull;
 		char	   *s;
 		char	   *name;
@@ -6246,9 +6245,29 @@ ProcessGUCArray(ArrayType *array,
 			continue;
 		}
 
-		(void) set_config_option(name, value,
+		if (usersetArray)
-								 context, source,
+			userSetDatum = array_ref(usersetArray, 1, &i,
-								 action, true, 0, false);
+									 -1 /* varlenarray */ ,
+									 sizeof(bool) /* BOOL's typlen */ ,
+									 true /* BOOL's typbyval */ ,
+									 TYPALIGN_CHAR /* BOOL's typalign */ ,
+									 &isnull);
+		if (isnull)
+			userSetDatum = BoolGetDatum(false);
+
+		/*
+		 * USER SET values are appliciable only for PGC_USERSET parameters. We
+		 * use InvalidOid as role in order to evade possible privileges of the
+		 * current user.
+		 */
+		if (!DatumGetBool(userSetDatum))
+			(void) set_config_option(name, value,
+									 context, source,
+									 action, true, 0, false);
+		else
+			(void) set_config_option_ext(name, value,
+										 PGC_USERSET, source, InvalidOid,
+										 action, true, 0, false);
 
 		pfree(name);
 		pfree(value);
@@ -6262,7 +6281,8 @@ ProcessGUCArray(ArrayType *array,
  * to indicate the current table entry is NULL.
  */
 ArrayType *
-GUCArrayAdd(ArrayType *array, const char *name, const char *value)
+GUCArrayAdd(ArrayType *array, ArrayType **usersetArray,
+			const char *name, const char *value, bool user_set)
 {
 	struct config_generic *record;
 	Datum		datum;
@@ -6273,7 +6293,7 @@ GUCArrayAdd(ArrayType *array, const char *name, const char *value)
 	Assert(value);
 
 	/* test if the option is valid and we're allowed to set it */
-	(void) validate_option_array_item(name, value, false);
+	(void) validate_option_array_item(name, value, user_set, false);
 
 	/* normalize name (converts obsolete GUC names to modern spellings) */
 	record = find_option(name, false, true, WARNING);
@@ -6314,6 +6334,27 @@ GUCArrayAdd(ArrayType *array, const char *name, const char *value)
 			/* check for match up through and including '=' */
 			if (strncmp(current, newval, strlen(name) + 1) == 0)
 			{
+				bool		currentUserSet = false;
+
+				if (usersetArray)
+				{
+					currentUserSet = DatumGetBool(array_ref(*usersetArray, 1, &i,
+															-1 /* varlenarray */ ,
+															sizeof(bool) /* BOOL's typlen */ ,
+															true /* BOOL's typbyval */ ,
+															TYPALIGN_CHAR /* BOOL's typalign */ ,
+															&isnull));
+					if (isnull)
+						currentUserSet = false;
+				}
+
+				/*
+				 * Recheck permissons if we found an option without USER SET
+				 * flag while we're setting an optionn with USER SET flag.
+				 */
+				if (!currentUserSet && user_set)
+					(void) validate_option_array_item(name, value,
+													  false, false);
 				index = i;
 				break;
 			}
@@ -6326,9 +6367,25 @@ GUCArrayAdd(ArrayType *array, const char *name, const char *value)
 					  -1 /* TEXT's typlen */ ,
 					  false /* TEXT's typbyval */ ,
 					  TYPALIGN_INT /* TEXT's typalign */ );
+
+		if (usersetArray)
+			*usersetArray = array_set(*usersetArray, 1, &index,
+									  BoolGetDatum(user_set),
+									  false,
+									  -1 /* varlena array */ ,
+									  sizeof(bool) /* BOOL's typlen */ ,
+									  true /* BOOL's typbyval */ ,
+									  TYPALIGN_CHAR /* BOOL's typalign */ );
 	}
 	else
+	{
 		a = construct_array_builtin(&datum, 1, TEXTOID);
+		if (usersetArray)
+		{
+			datum = BoolGetDatum(user_set);
+			*usersetArray = construct_array_builtin(&datum, 1, BOOLOID);
+		}
+	}
 
 	return a;
 }
@@ -6340,18 +6397,16 @@ GUCArrayAdd(ArrayType *array, const char *name, const char *value)
  * is NULL then a null should be stored.
  */
 ArrayType *
-GUCArrayDelete(ArrayType *array, const char *name)
+GUCArrayDelete(ArrayType *array, ArrayType **usersetArray, const char *name)
 {
 	struct config_generic *record;
 	ArrayType  *newarray;
+	ArrayType  *newUsersetArray;
 	int			i;
 	int			index;
 
 	Assert(name);
 
-	/* test if the option is valid and we're allowed to set it */
-	(void) validate_option_array_item(name, NULL, false);
-
 	/* normalize name (converts obsolete GUC names to modern spellings) */
 	record = find_option(name, false, true, WARNING);
 	if (record)
@@ -6362,11 +6417,13 @@ GUCArrayDelete(ArrayType *array, const char *name)
 		return NULL;
 
 	newarray = NULL;
+	newUsersetArray = NULL;
 	index = 1;
 
 	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
 	{
 		Datum		d;
+		Datum		userSetDatum = BoolGetDatum(false);
 		char	   *val;
 		bool		isnull;
 
@@ -6380,13 +6437,29 @@ GUCArrayDelete(ArrayType *array, const char *name)
 			continue;
 		val = TextDatumGetCString(d);
 
+		if (usersetArray)
+			userSetDatum = array_ref(*usersetArray, 1, &i,
+									 -1 /* varlenarray */ ,
+									 sizeof(bool) /* BOOL's typlen */ ,
+									 true /* BOOL's typbyval */ ,
+									 TYPALIGN_CHAR /* BOOL's typalign */ ,
+									 &isnull);
+		if (isnull)
+			userSetDatum = BoolGetDatum(false);
+
 		/* ignore entry if it's what we want to delete */
 		if (strncmp(val, name, strlen(name)) == 0
 			&& val[strlen(name)] == '=')
+		{
+			/* test if the option is valid and we're allowed to set it */
+			(void) validate_option_array_item(name, NULL,
+											  DatumGetBool(userSetDatum), false);
 			continue;
+		}
 
 		/* else add it to the output array */
 		if (newarray)
+		{
 			newarray = array_set(newarray, 1, &index,
 								 d,
 								 false,
@@ -6394,12 +6467,28 @@ GUCArrayDelete(ArrayType *array, const char *name)
 								 -1 /* TEXT's typlen */ ,
 								 false /* TEXT's typbyval */ ,
 								 TYPALIGN_INT /* TEXT's typalign */ );
+			if (usersetArray)
+				newUsersetArray = array_set(newUsersetArray, 1, &index,
+											userSetDatum,
+											false,
+											-1 /* varlena array */ ,
+											sizeof(bool) /* BOOL's typlen */ ,
+											true /* BOOL's typbyval */ ,
+											TYPALIGN_CHAR /* BOOL's typalign */ );
+		}
 		else
+		{
 			newarray = construct_array_builtin(&d, 1, TEXTOID);
+			if (usersetArray)
+				newUsersetArray = construct_array_builtin(&d, 1, BOOLOID);
+		}
 
 		index++;
 	}
 
+	if (usersetArray)
+		*usersetArray = newUsersetArray;
+
 	return newarray;
 }
 
@@ -6410,9 +6499,10 @@ GUCArrayDelete(ArrayType *array, const char *name)
  * those that are PGC_USERSET or we have permission to set
  */
 ArrayType *
-GUCArrayReset(ArrayType *array)
+GUCArrayReset(ArrayType *array, ArrayType **usersetArray)
 {
 	ArrayType  *newarray;
+	ArrayType  *newUsersetArray;
 	int			i;
 	int			index;
 
@@ -6425,11 +6515,13 @@ GUCArrayReset(ArrayType *array)
 		return NULL;
 
 	newarray = NULL;
+	newUsersetArray = NULL;
 	index = 1;
 
 	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
 	{
 		Datum		d;
+		Datum		userSetDatum = BoolGetDatum(false);
 		char	   *val;
 		char	   *eqsgn;
 		bool		isnull;
@@ -6444,15 +6536,27 @@ GUCArrayReset(ArrayType *array)
 			continue;
 		val = TextDatumGetCString(d);
 
+		if (usersetArray)
+			userSetDatum = array_ref(*usersetArray, 1, &i,
+									 -1 /* varlenarray */ ,
+									 sizeof(bool) /* BOOL's typlen */ ,
+									 true /* BOOL's typbyval */ ,
+									 TYPALIGN_CHAR /* BOOL's typalign */ ,
+									 &isnull);
+		if (isnull)
+			userSetDatum = BoolGetDatum(false);
+
 		eqsgn = strchr(val, '=');
 		*eqsgn = '\0';
 
 		/* skip if we have permission to delete it */
-		if (validate_option_array_item(val, NULL, true))
+		if (validate_option_array_item(val, NULL,
+									   DatumGetBool(userSetDatum), true))
 			continue;
 
 		/* else add it to the output array */
 		if (newarray)
+		{
 			newarray = array_set(newarray, 1, &index,
 								 d,
 								 false,
@@ -6460,13 +6564,29 @@ GUCArrayReset(ArrayType *array)
 								 -1 /* TEXT's typlen */ ,
 								 false /* TEXT's typbyval */ ,
 								 TYPALIGN_INT /* TEXT's typalign */ );
+			if (usersetArray)
+				newUsersetArray = array_set(newUsersetArray, 1, &index,
+											userSetDatum,
+											false,
+											-1 /* varlena array */ ,
+											sizeof(bool) /* BOOL's typlen */ ,
+											true /* BOOL's typbyval */ ,
+											TYPALIGN_CHAR /* BOOL's typalign */ );
+		}
 		else
+		{
 			newarray = construct_array_builtin(&d, 1, TEXTOID);
+			if (usersetArray)
+				newUsersetArray = construct_array_builtin(&userSetDatum, 1, BOOLOID);
+		}
 
 		index++;
 		pfree(val);
 	}
 
+	if (usersetArray)
+		*usersetArray = newUsersetArray;
+
 	return newarray;
 }
 
@@ -6474,15 +6594,16 @@ GUCArrayReset(ArrayType *array)
  * Validate a proposed option setting for GUCArrayAdd/Delete/Reset.
  *
  * name is the option name.  value is the proposed value for the Add case,
- * or NULL for the Delete/Reset cases.  If skipIfNoPermissions is true, it's
+ * or NULL for the Delete/Reset cases.  user_set indicates this is the USER SET
- * not an error to have no permissions to set the option.
+ * option.  If skipIfNoPermissions is true, it's not an error to have no
+ * permissions to set the option.
  *
  * Returns true if OK, false if skipIfNoPermissions is true and user does not
  * have permission to change this option (all other error cases result in an
  * error being thrown).
  */
 static bool
-validate_option_array_item(const char *name, const char *value,
+validate_option_array_item(const char *name, const char *value, bool user_set,
 						   bool skipIfNoPermissions)
 
 {
@@ -6518,8 +6639,10 @@ validate_option_array_item(const char *name, const char *value,
 	{
 		/*
 		 * We cannot do any meaningful check on the value, so only permissions
-		 * are useful to check.
+		 * are useful to check.  USER SET options are always allowed.
 		 */
+		if (user_set)
+			return true;
 		if (superuser() ||
 			pg_parameter_aclcheck(name, GetUserId(), ACL_SET) == ACLCHECK_OK)
 			return true;

src/backend/utils/misc/guc_funcs.c

@@ -166,12 +166,22 @@ ExecSetVariableStmt(VariableSetStmt *stmt, bool isTopLevel)
 char *
 ExtractSetVariableArgs(VariableSetStmt *stmt)
 {
+
 	switch (stmt->kind)
 	{
 		case VAR_SET_VALUE:
 			return flatten_set_variable_args(stmt->name, stmt->args);
 		case VAR_SET_CURRENT:
-			return GetConfigOptionByName(stmt->name, NULL, false);
+			{
+				struct config_generic *record;
+				char	   *result;
+
+				result = GetConfigOptionByName(stmt->name, NULL, false);
+				record = find_option(stmt->name, false, false, ERROR);
+				stmt->user_set = (record->scontext == PGC_USERSET);
+
+				return result;
+			}
 		default:
 			return NULL;
 	}

src/bin/pg_dump/dumputils.c

@@ -816,6 +816,7 @@ SplitGUCList(char *rawstring, char separator,
  */
 void
 makeAlterConfigCommand(PGconn *conn, const char *configitem,
+					   const char *userset,
 					   const char *type, const char *name,
 					   const char *type2, const char *name2,
 					   PQExpBuffer buf)
@@ -874,6 +875,10 @@ makeAlterConfigCommand(PGconn *conn, const char *configitem,
 	else
 		appendStringLiteralConn(buf, pos, conn);
 
+	/* Add USER SET flag if specified in the string */
+	if (userset && !strcmp(userset, "t"))
+		appendPQExpBufferStr(buf, " USER SET");
+
 	appendPQExpBufferStr(buf, ";\n");
 
 	pg_free(mine);

src/bin/pg_dump/dumputils.h

@@ -59,6 +59,7 @@ extern bool SplitGUCList(char *rawstring, char separator,
 						 char ***namelist);
 
 extern void makeAlterConfigCommand(PGconn *conn, const char *configitem,
+								   const char *userset,
 								   const char *type, const char *name,
 								   const char *type2, const char *name2,
 								   PQExpBuffer buf);

src/bin/pg_dump/pg_dump.c

@@ -3270,32 +3270,49 @@ dumpDatabaseConfig(Archive *AH, PQExpBuffer outbuf,
 	PGresult   *res;
 
 	/* First collect database-specific options */
-	printfPQExpBuffer(buf, "SELECT unnest(setconfig) FROM pg_db_role_setting "
+	printfPQExpBuffer(buf, "SELECT unnest(setconfig)");
+	if (AH->remoteVersion >= 160000)
+		appendPQExpBufferStr(buf, ", unnest(setuser)");
+	appendPQExpBuffer(buf, " FROM pg_db_role_setting "
 					  "WHERE setrole = 0 AND setdatabase = '%u'::oid",
 					  dboid);
 
 	res = ExecuteSqlQuery(AH, buf->data, PGRES_TUPLES_OK);
 
 	for (int i = 0; i < PQntuples(res); i++)
-		makeAlterConfigCommand(conn, PQgetvalue(res, i, 0),
+	{
+		char	   *userset = NULL;
+
+		if (AH->remoteVersion >= 160000)
+			userset = PQgetvalue(res, i, 1);
+		makeAlterConfigCommand(conn, PQgetvalue(res, i, 0), userset,
 							   "DATABASE", dbname, NULL, NULL,
 							   outbuf);
+	}
 
 	PQclear(res);
 
 	/* Now look for role-and-database-specific options */
-	printfPQExpBuffer(buf, "SELECT rolname, unnest(setconfig) "
+	printfPQExpBuffer(buf, "SELECT rolname, unnest(setconfig)");
-					  "FROM pg_db_role_setting s, pg_roles r "
+	if (AH->remoteVersion >= 160000)
+		appendPQExpBufferStr(buf, ", unnest(setuser)");
+	appendPQExpBuffer(buf, " FROM pg_db_role_setting s, pg_roles r "
 					  "WHERE setrole = r.oid AND setdatabase = '%u'::oid",
 					  dboid);
 
 	res = ExecuteSqlQuery(AH, buf->data, PGRES_TUPLES_OK);
 
 	for (int i = 0; i < PQntuples(res); i++)
-		makeAlterConfigCommand(conn, PQgetvalue(res, i, 1),
+	{
+		char	   *userset = NULL;
+
+		if (AH->remoteVersion >= 160000)
+			userset = PQgetvalue(res, i, 2);
+		makeAlterConfigCommand(conn, PQgetvalue(res, i, 1), userset,
 							   "ROLE", PQgetvalue(res, i, 0),
 							   "DATABASE", dbname,
 							   outbuf);
+	}
 
 	PQclear(res);
 

src/bin/pg_dump/pg_dumpall.c

@@ -1384,7 +1384,10 @@ dumpUserConfig(PGconn *conn, const char *username)
 	PQExpBuffer buf = createPQExpBuffer();
 	PGresult   *res;
 
-	printfPQExpBuffer(buf, "SELECT unnest(setconfig) FROM pg_db_role_setting "
+	printfPQExpBuffer(buf, "SELECT unnest(setconfig)");
+	if (server_version >= 160000)
+		appendPQExpBufferStr(buf, ", unnest(setuser)");
+	appendPQExpBuffer(buf, " FROM pg_db_role_setting "
 					  "WHERE setdatabase = 0 AND setrole = "
 					  "(SELECT oid FROM %s WHERE rolname = ",
 					  role_catalog);
@@ -1398,8 +1401,13 @@ dumpUserConfig(PGconn *conn, const char *username)
 
 	for (int i = 0; i < PQntuples(res); i++)
 	{
+		char	*userset = NULL;
+
+		if (server_version >= 160000)
+			userset = PQgetvalue(res, i, 1);
+
 		resetPQExpBuffer(buf);
-		makeAlterConfigCommand(conn, PQgetvalue(res, i, 0),
+		makeAlterConfigCommand(conn, PQgetvalue(res, i, 0), userset,
 							   "ROLE", username, NULL, NULL,
 							   buf);
 		fprintf(OPF, "%s", buf->data);

src/bin/psql/describe.c

@@ -3769,13 +3769,16 @@ listDbRoleSettings(const char *pattern, const char *pattern2)
 	initPQExpBuffer(&buf);
 
 	printfPQExpBuffer(&buf, "SELECT rolname AS \"%s\", datname AS \"%s\",\n"
-					  "pg_catalog.array_to_string(setconfig, E'\\n') AS \"%s\"\n"
+					  "pg_catalog.array_to_string(setconfig, E'\\n') AS \"%s\"",
-					  "FROM pg_catalog.pg_db_role_setting s\n"
-					  "LEFT JOIN pg_catalog.pg_database d ON d.oid = setdatabase\n"
-					  "LEFT JOIN pg_catalog.pg_roles r ON r.oid = setrole\n",
 					  gettext_noop("Role"),
 					  gettext_noop("Database"),
 					  gettext_noop("Settings"));
+	if (pset.sversion >= 160000)
+		appendPQExpBuffer(&buf, ",\npg_catalog.array_to_string(setuser, E'\\n') AS \"%s\"",
+						  gettext_noop("User set"));
+	appendPQExpBuffer(&buf, "\nFROM pg_catalog.pg_db_role_setting s\n"
+					  "LEFT JOIN pg_catalog.pg_database d ON d.oid = setdatabase\n"
+					  "LEFT JOIN pg_catalog.pg_roles r ON r.oid = setrole\n");
 	if (!validateSQLNamePattern(&buf, pattern, false, false,
 								NULL, "r.rolname", NULL, NULL, &havewhere, 1))
 		goto error_return;

src/bin/psql/tab-complete.c

@@ -4442,6 +4442,10 @@ psql_completion(const char *text, int start, int end)
 			}
 		}
 	}
+	/* Complete ALTER DATABASE|ROLE|USER ... SET ... TO ... USER SET */
+	else if (HeadMatches("ALTER", "DATABASE|ROLE|USER") &&
+			 TailMatches("SET", MatchAny, "TO|=", MatchAny))
+		COMPLETE_WITH("USER SET");
 
 /* START TRANSACTION */
 	else if (Matches("START"))

src/include/catalog/catversion.h

@@ -57,6 +57,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202212061
+#define CATALOG_VERSION_NO	202212091
 
 #endif

src/include/catalog/pg_db_role_setting.h

@@ -41,6 +41,8 @@ CATALOG(pg_db_role_setting,2964,DbRoleSettingRelationId) BKI_SHARED_RELATION
 
 #ifdef CATALOG_VARLEN			/* variable-length fields start here */
 	text		setconfig[1];	/* GUC settings to apply at login */
+
+	bool		setuser[1];		/* USER SET flags for GUC settings */
 #endif
 } FormData_pg_db_role_setting;
 

src/include/nodes/parsenodes.h

@@ -2257,6 +2257,7 @@ typedef struct VariableSetStmt
 	char	   *name;			/* variable to be set */
 	List	   *args;			/* List of A_Const nodes */
 	bool		is_local;		/* SET LOCAL? */
+	bool		user_set;
 } VariableSetStmt;
 
 /* ----------------------

src/include/utils/guc.h

@@ -391,11 +391,14 @@ extern void AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt);
 extern char *GetConfigOptionByName(const char *name, const char **varname,
 								   bool missing_ok);
 
-extern void ProcessGUCArray(ArrayType *array,
+extern void ProcessGUCArray(ArrayType *array, ArrayType *usersetArray,
 							GucContext context, GucSource source, GucAction action);
-extern ArrayType *GUCArrayAdd(ArrayType *array, const char *name, const char *value);
+extern ArrayType *GUCArrayAdd(ArrayType *array, ArrayType **usersetArray,
-extern ArrayType *GUCArrayDelete(ArrayType *array, const char *name);
+							  const char *name, const char *value,
-extern ArrayType *GUCArrayReset(ArrayType *array);
+							  bool user_set);
+extern ArrayType *GUCArrayDelete(ArrayType *array, ArrayType **usersetArray,
+								 const char *name);
+extern ArrayType *GUCArrayReset(ArrayType *array, ArrayType **usersetArray);
 
 extern void *guc_malloc(int elevel, size_t size);
 extern pg_nodiscard void *guc_realloc(int elevel, void *old, size_t size);

src/test/modules/Makefile

@@ -25,6 +25,7 @@ SUBDIRS = \
 		  test_misc \
 		  test_oat_hooks \
 		  test_parser \
+		  test_pg_db_role_setting \
 		  test_pg_dump \
 		  test_predtest \
 		  test_rbtree \

src/test/modules/meson.build

@@ -19,6 +19,7 @@ subdir('test_lfind')
 subdir('test_misc')
 subdir('test_oat_hooks')
 subdir('test_parser')
+subdir('test_pg_db_role_setting')
 subdir('test_pg_dump')
 subdir('test_predtest')
 subdir('test_rbtree')

src/test/modules/test_pg_db_role_setting/.gitignore

@@ -0,0 +1,4 @@
+# Generated subdirectories
+/log/
+/results/
+/tmp_check/

src/test/modules/test_pg_db_role_setting/Makefile

@@ -0,0 +1,29 @@
+# src/test/modules/test_pg_db_role_setting/Makefile
+
+MODULE_big = test_pg_db_role_setting
+OBJS = \
+	$(WIN32RES) \
+	test_pg_db_role_setting.o
+EXTENSION = test_pg_db_role_setting
+DATA = test_pg_db_role_setting--1.0.sql
+
+PGFILEDESC = "test_pg_db_role_setting - tests for default GUC values stored in pg_db_role_settings"
+
+REGRESS = test_pg_db_role_setting
+
+# disable installcheck for now
+NO_INSTALLCHECK = 1
+# and also for now force NO_LOCALE and UTF8
+ENCODING = UTF8
+NO_LOCALE = 1
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/test_pg_db_role_setting
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif

src/test/modules/test_pg_db_role_setting/expected/test_pg_db_role_setting.out

@@ -0,0 +1,143 @@
+CREATE EXTENSION test_pg_db_role_setting;
+CREATE USER super_user SUPERUSER;
+CREATE USER regular_user;
+\c - regular_user
+-- successfully set a placeholder value
+SET test_pg_db_role_setting.superuser_param = 'aaa';
+-- module is loaded, the placeholder value is thrown away
+SELECT load_test_pg_db_role_setting();
+WARNING:  permission denied to set parameter "test_pg_db_role_setting.superuser_param"
+ load_test_pg_db_role_setting 
+------------------------------
+ 
+(1 row)
+
+SHOW test_pg_db_role_setting.superuser_param;
+ test_pg_db_role_setting.superuser_param 
+-----------------------------------------
+ superuser_param_value
+(1 row)
+
+SHOW test_pg_db_role_setting.user_param;
+ test_pg_db_role_setting.user_param 
+------------------------------------
+ user_param_value
+(1 row)
+
+\c - regular_user
+-- fail, not privileges
+ALTER ROLE regular_user SET test_pg_db_role_setting.superuser_param = 'aaa';
+ERROR:  permission denied to set parameter "test_pg_db_role_setting.superuser_param"
+ALTER ROLE regular_user SET test_pg_db_role_setting.user_param = 'bbb';
+ERROR:  permission denied to set parameter "test_pg_db_role_setting.user_param"
+-- success for USER SET parameters
+ALTER ROLE regular_user SET test_pg_db_role_setting.superuser_param = 'aaa' USER SET;
+ALTER ROLE regular_user SET test_pg_db_role_setting.user_param = 'bbb' USER SET;
+\drds regular_user
+                                 List of settings
+     Role     | Database |                  Settings                   | User set 
+--------------+----------+---------------------------------------------+----------
+ regular_user |          | test_pg_db_role_setting.superuser_param=aaa+| t       +
+              |          | test_pg_db_role_setting.user_param=bbb      | t
+(1 row)
+
+\c - regular_user
+-- successfully set placeholders
+SHOW test_pg_db_role_setting.superuser_param;
+ test_pg_db_role_setting.superuser_param 
+-----------------------------------------
+ aaa
+(1 row)
+
+SHOW test_pg_db_role_setting.user_param;
+ test_pg_db_role_setting.user_param 
+------------------------------------
+ bbb
+(1 row)
+
+-- module is loaded, the placeholder value of superuser param is thrown away
+SELECT load_test_pg_db_role_setting();
+WARNING:  permission denied to set parameter "test_pg_db_role_setting.superuser_param"
+ load_test_pg_db_role_setting 
+------------------------------
+ 
+(1 row)
+
+SHOW test_pg_db_role_setting.superuser_param;
+ test_pg_db_role_setting.superuser_param 
+-----------------------------------------
+ superuser_param_value
+(1 row)
+
+SHOW test_pg_db_role_setting.user_param;
+ test_pg_db_role_setting.user_param 
+------------------------------------
+ bbb
+(1 row)
+
+\c - super_user
+ALTER ROLE regular_user SET test_pg_db_role_setting.superuser_param = 'aaa';
+\drds regular_user
+                                 List of settings
+     Role     | Database |                  Settings                   | User set 
+--------------+----------+---------------------------------------------+----------
+ regular_user |          | test_pg_db_role_setting.superuser_param=aaa+| f       +
+              |          | test_pg_db_role_setting.user_param=bbb      | t
+(1 row)
+
+\c - regular_user
+-- don't have a priviledge to change superuser value to user set one
+ALTER ROLE regular_user SET test_pg_db_role_setting.superuser_param = 'ccc' USER SET;
+ERROR:  permission denied to set parameter "test_pg_db_role_setting.superuser_param"
+\c - super_user
+SELECT load_test_pg_db_role_setting();
+ load_test_pg_db_role_setting 
+------------------------------
+ 
+(1 row)
+
+-- give the privilege to set SUSET param to the regular user
+GRANT SET ON PARAMETER test_pg_db_role_setting.superuser_param TO regular_user;
+\c - regular_user
+ALTER ROLE regular_user SET test_pg_db_role_setting.superuser_param = 'ccc';
+\drds regular_user
+                                 List of settings
+     Role     | Database |                  Settings                   | User set 
+--------------+----------+---------------------------------------------+----------
+ regular_user |          | test_pg_db_role_setting.superuser_param=ccc+| f       +
+              |          | test_pg_db_role_setting.user_param=bbb      | t
+(1 row)
+
+\c - regular_user
+-- successfully set placeholders
+SHOW test_pg_db_role_setting.superuser_param;
+ test_pg_db_role_setting.superuser_param 
+-----------------------------------------
+ ccc
+(1 row)
+
+SHOW test_pg_db_role_setting.user_param;
+ test_pg_db_role_setting.user_param 
+------------------------------------
+ bbb
+(1 row)
+
+-- module is loaded, and placeholder values are succesfully set
+SELECT load_test_pg_db_role_setting();
+ load_test_pg_db_role_setting 
+------------------------------
+ 
+(1 row)
+
+SHOW test_pg_db_role_setting.superuser_param;
+ test_pg_db_role_setting.superuser_param 
+-----------------------------------------
+ ccc
+(1 row)
+
+SHOW test_pg_db_role_setting.user_param;
+ test_pg_db_role_setting.user_param 
+------------------------------------
+ bbb
+(1 row)
+

src/test/modules/test_pg_db_role_setting/meson.build

@@ -0,0 +1,35 @@
+# FIXME: prevent install during main install, but not during test :/
+
+test_pg_db_role_setting_sources = files(
+  'test_pg_db_role_setting.c',
+)
+
+if host_system == 'windows'
+  test_pg_db_role_setting_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+    '--NAME', 'test_pg_db_role_setting',
+    '--FILEDESC', 'test_pg_db_role_setting - tests for default GUC values stored in pg_db_role_settings',])
+endif
+
+test_pg_db_role_setting = shared_module('test_pg_db_role_setting',
+  test_pg_db_role_setting_sources,
+  kwargs: pg_mod_args,
+)
+testprep_targets += test_pg_db_role_setting
+
+install_data(
+  'test_pg_db_role_setting.control',
+  'test_pg_db_role_setting--1.0.sql',
+  kwargs: contrib_data_args,
+)
+
+tests += {
+  'name': 'test_pg_db_role_setting',
+  'sd': meson.current_source_dir(),
+  'bd': meson.current_build_dir(),
+  'regress': {
+    'sql': [
+      'test_pg_db_role_setting',
+    ],
+    'regress_args': ['--no-locale', '--encoding=UTF8'],
+  },
+}

src/test/modules/test_pg_db_role_setting/sql/test_pg_db_role_setting.sql

@@ -0,0 +1,63 @@
+CREATE EXTENSION test_pg_db_role_setting;
+CREATE USER super_user SUPERUSER;
+CREATE USER regular_user;
+
+\c - regular_user
+-- successfully set a placeholder value
+SET test_pg_db_role_setting.superuser_param = 'aaa';
+
+-- module is loaded, the placeholder value is thrown away
+SELECT load_test_pg_db_role_setting();
+
+SHOW test_pg_db_role_setting.superuser_param;
+SHOW test_pg_db_role_setting.user_param;
+
+\c - regular_user
+-- fail, not privileges
+ALTER ROLE regular_user SET test_pg_db_role_setting.superuser_param = 'aaa';
+ALTER ROLE regular_user SET test_pg_db_role_setting.user_param = 'bbb';
+-- success for USER SET parameters
+ALTER ROLE regular_user SET test_pg_db_role_setting.superuser_param = 'aaa' USER SET;
+ALTER ROLE regular_user SET test_pg_db_role_setting.user_param = 'bbb' USER SET;
+
+\drds regular_user
+
+\c - regular_user
+-- successfully set placeholders
+SHOW test_pg_db_role_setting.superuser_param;
+SHOW test_pg_db_role_setting.user_param;
+
+-- module is loaded, the placeholder value of superuser param is thrown away
+SELECT load_test_pg_db_role_setting();
+
+SHOW test_pg_db_role_setting.superuser_param;
+SHOW test_pg_db_role_setting.user_param;
+
+\c - super_user
+ALTER ROLE regular_user SET test_pg_db_role_setting.superuser_param = 'aaa';
+\drds regular_user
+
+\c - regular_user
+-- don't have a priviledge to change superuser value to user set one
+ALTER ROLE regular_user SET test_pg_db_role_setting.superuser_param = 'ccc' USER SET;
+
+\c - super_user
+SELECT load_test_pg_db_role_setting();
+-- give the privilege to set SUSET param to the regular user
+GRANT SET ON PARAMETER test_pg_db_role_setting.superuser_param TO regular_user;
+
+\c - regular_user
+ALTER ROLE regular_user SET test_pg_db_role_setting.superuser_param = 'ccc';
+
+\drds regular_user
+
+\c - regular_user
+-- successfully set placeholders
+SHOW test_pg_db_role_setting.superuser_param;
+SHOW test_pg_db_role_setting.user_param;
+
+-- module is loaded, and placeholder values are succesfully set
+SELECT load_test_pg_db_role_setting();
+
+SHOW test_pg_db_role_setting.superuser_param;
+SHOW test_pg_db_role_setting.user_param;

src/test/modules/test_pg_db_role_setting/test_pg_db_role_setting--1.0.sql

@@ -0,0 +1,7 @@
+/* src/test/modules/test_pg_db_role_setting/test_pg_db_role_setting--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION test_pg_db_role_setting" to load this file. \quit
+
+CREATE FUNCTION load_test_pg_db_role_setting() RETURNS void
+  AS 'MODULE_PATHNAME' LANGUAGE C;

src/test/modules/test_pg_db_role_setting/test_pg_db_role_setting.c

@@ -0,0 +1,57 @@
+/*--------------------------------------------------------------------------
+ *
+ * test_pg_db_role_setting.c
+ *		Code for testing mandatory access control (MAC) using object access hooks.
+ *
+ * Copyright (c) 2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		src/test/modules/test_pg_db_role_setting/test_pg_db_role_setting.c
+ *
+ * -------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "utils/guc.h"
+
+PG_MODULE_MAGIC;
+
+PG_FUNCTION_INFO_V1(load_test_pg_db_role_setting);
+
+static char *superuser_param;
+static char *user_param;
+
+/*
+ * Module load callback
+ */
+void
+_PG_init(void)
+{
+	DefineCustomStringVariable("test_pg_db_role_setting.superuser_param",
+							   "Sample superuser parameter.",
+							   NULL,
+							   &superuser_param,
+							   "superuser_param_value",
+							   PGC_SUSET,
+							   0,
+							   NULL, NULL, NULL);
+
+	DefineCustomStringVariable("test_pg_db_role_setting.user_param",
+							   "Sample user parameter.",
+							   NULL,
+							   &user_param,
+							   "user_param_value",
+							   PGC_USERSET,
+							   0,
+							   NULL, NULL, NULL);
+}
+
+/*
+ * Empty function, which is used just to trigger load of this module.
+ */
+Datum
+load_test_pg_db_role_setting(PG_FUNCTION_ARGS)
+{
+	PG_RETURN_VOID();
+}

src/test/modules/test_pg_db_role_setting/test_pg_db_role_setting.control

@@ -0,0 +1,7 @@
+# test_pg_db_role_setting extension
+comment = 'test_pg_db_role_setting - tests for default GUC values stored in pg_db_role_setting'
+default_version = '1.0'
+module_pathname = '$libdir/test_pg_db_role_setting'
+relocatable = true
+superuser = false
+trusted = true

src/test/regress/expected/psql.out

@@ -6188,9 +6188,9 @@ List of schemas
 (0 rows)
 
 \drds "no.such.setting"
-      List of settings
+           List of settings
- Role | Database | Settings 
+ Role | Database | Settings | User set 
-------+----------+----------
+------+----------+----------+----------
 (0 rows)
 
 \dRp "no.such.publication"